Antifriction screw device



April 23, 1946. H. S. HOFFAR 2,398,789

ANTIFRICTION SCREW DEVICE Filed May 5, 1943 2 Sheets-Sheet l 1 INVENTOR Henry S. HcF-Far ATTORNEY ANTIFRICTION SCREW DEVICE Filed May s, 1943 2 Sheets-Sheet 2 4 INVENTOR Henry S. Hoffar BY ATTORN EY V Patented Apr. 23, 1946 UNl TED sures- ATEN orrlca ANTIFRICTION SCREW DEVICE Henry S. Hoii'ar, West Vancouver, British Columbia, Canada, assignor, by mesne assignments, to The Cleveland Pneumatic Tool Company,

Cleveland, Ohio, acorporatlon of Ohio Application May a, 1943, Serial No. 485,423

' 2 Claims. (Cl. 74-459) The present invention relates to anti-frictionscrew devices and more particularly to improvements in such devices as illustrated in my Patent Number 2,298,011, granted October 6, 1942.

Anti-friction screw devices of the type disclosed in my patent which employ circulating balls for interconnecting the nut and screw have heretofore been so constructed that the screw member is longer than the nut member and the balls have been made to circulate through the nut by way of a by-pass formed therein.

In accordance with the present invention, the construction is such that the nut is the longer member and the screw is the shorter member with the balls being circulated through the screw rather than through the nut; suitable deflecting mean and by-pas being provided in the screw. From this construction, it will be readily apparcut that it is possible to enclose the grooved members entirely and thus retain any lubricant employed while excluding dirt, dust and other foreign matter. Th primary object of the invention is, therefore, to provide an anti-friction screw device of the recirculating ball type, the construction of which makes it possible to enclose completely certain of the moving parts to thus effectively lubricate said parts while substantially excluding dirt, dust and other foreign matter therefrom.

Another object of the invention resides in the provision of means whereby anti-friction screw and nut devices of the recirculating ball type may be improved in construction and operation.

Other object and advantages more or less ancillary to the foregoing reside in the specific construction and aggroupment of the elements peculiar to-this structure, as will become apparent from a more complete examination of this specification.

In the drawings which illustrate the invention: ,Fig. 1 is an enlarged longitudinal ectional view illustrating an anti-friction screw device constructed in accordance with the present inven tion in use with a lifting jack. .Fig. 2 is a fragmentary sectional view of the mechanism removed from the jack.

Fig. 3 is a vertical sectional view taken substan-- tially on line 3-3 of Fig. 2.

Fig. 4 is a vertical sectional view taken substantially on line 4-4 of Fig. 2.

Referring to the drawing for a more detailed description thereof, and particularly Fig. 1 wherein there is disclosed a practical application of the invention, a lifting jack of the screw type is generally designated by the referenc numeral 8,

and include a housing 1 and rotating mechanism 8 attached thereto and extending at right angles therefrom. In the illustration shown, the housing 1 is formed of upper and lower sections 9 and Ill united by means of bolts or the like ll, while the upper section 9 is provided with a cap l2 which is detachably connected thereto by machine screws l3.

Thehousing I rotatably supports the relatively long member l4,hereinafter termed the nut, said nut being formed with helically inclined grooves !5 throughout its length and said grooves being slightly less than semi-circular in cross section.

' The nut I4 is supported in the housing 1 on bearings l6 and IT, a packing sleeve l8 surrounding the lower end of the nut I 4 and in engagement with the lower bearing ll.

The jack 6 further includes a sleeve l9 on the upper end of the nut H, which sleeve rests upon the upper bearings IS. The mechanism for rotating the nut It includes a beveled gear 20 keyed to the sleeve 1 9 and upper end of the nut It by means of the screws 2|, said gear 20 being in mesh with a pinion gear 22 carried on the inner end of the operating shaft 23 and secured thereto by means of a pin or the like 24. Since thegears and their associated mechanism form no part of the present invention, it is not deemed necessary to completely describe their construction and operation. It i to be understood, however, that the jack mechanism is raised and lowered by rotation of the shaft 23 to drivingly engage the gears 20 and 22. As the gear 20 is rotated, the construction whereby it is keyed to the sleeve l9 and upper end of the nut I lwill rotate those parts to raise and lower the shaft 29 carried thereby.

Referring to Figs. 2, 3 and 4 for a more detailed illustration of the anti-friction screw device, it will be noted that the rotating screw unit is a relatively short member whose exterior diameter is sl ghtly smaller than the interior diameter of the nut It. The screw 25 is formed with an an terior helically inclined channel 25 of slightly less than semi-circular cross section, such screw unit channel forming with'the channel IS in the nut 14 a helical ball-accommodating duct or orbit for theballs 21 and 28, which interconnect the screw unit and the nut. As in my patent, it is p oposed to use alternate large and small balls mean of a nut 30 and lock screw 88. An amal ball-accommodating groove 32, which i preferably slightly larger in diameter than the larger balls 21, is formed in the rod 28, each end of said groove being in communication with a drilled aperture 33 formed in each end of the sleeve 25, for afiording communication with the sleeves exterior helical channel. A deflector 35, best shown in Fig. 3 of the drawings, is positioned adjacent each aperture 33' and guides the balls in their travel from the helical channel into the apertures 33 for passage through the groove 82, o out of such groove into the channel. As shown in Fig. l, the rod 29 is further secured to the screw sleeve 25 by a threaded key 36 which is positioned in advance or the nut 86.

From the above description when taken in connection with the accompanying drawings, it will be readily apparent that rotation of the nut id in either direction will cause axial movement of the rod 29 through the interconnection of the 'screw sleeve 25 and the nut by the balls received'in their helical channels. As the nut Ed is rotated relative to the screw 25, the alternate large and small bal s 27 and 28, respectively, will travel through the helical bail-accommodating duct formed cooperatively by the nut and screw helical channels, and will be directed in their travel by the deflectors 35 for passage through the groove 32. Thus the circulating balls will interconnect the nut and screw and transmit axial forces from one to the other. From the construction shown in Fig. 1, it will be seen that it is possible to enclose mplet y the channels of the nut and screw, respectively, as well as the circulating balls and thus retain any lubricant employed for the moving parts. The lower end of the housing 7 is provided with a suitabl packing 35 which will aid in retaining the lubricant and at the same time prevent the admission of dirt, dust and other foreign matter.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modifications of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

asoarso I claim: 1. An anti-friction screw mechanism comprising a relatively long nut having an internal helical channel, a rod withinsaid nut including a nally thereof a ball-accommodating groove which is closed at its ends, a sleeve relatively hort as compared to said nut and snugly engaged over said rod portion and covering said groove to form thereof a ball bypass duct, said sleeve having an exterior helical channel complemental to and cooperating with the helical channel of said nut to define between said nut and said sleeve a helical ball-accommodating duct, said sleeve also having two apertures spaced apart longitudinally thereof and extending therethrough and wording communication between said helical ball-accommodating duct and th ends, respectively, of said ball by-pass duct, means securing said rod and said sleeve together as a unit, a eries of balls disposed in said ducts whereby relative rotation of said nut and said rod and sleeve unit efiects relative longitudinal movement between said nut and said unit, and means to cause said balls to circulate through said ducts in response to relative rotation of said nut and said unit.

2. An anti-friction screw mechanism comprising a rod having therein and extending longitudinally thereof a ball-accommodating groove which is closed at its ends, a sleeve engaged snugly over said rod and covering said groove to form thereof a ball by-pass duct, said sleeve having an exterior helical channel and further having two apertures spaced apart longitudinally thereof and extending therethrough and affording communication between said helical channel and the ends, respectively, of said ball by-pass duct, means securing said rod and said sleeve together a a unit, a member having a helical channel complemental to and cooperating with the helical channel of said sleeve to define between said sleeve and said member a helical ball-accommodating duct, a series' of balls disposed in said ducts, those in said helical ball-accommodating duct interconnecting said unit and said member, and means to cause said balls to circulate through said ducts in response to relative rotation of said unit and said member.

HENRY S. HOFFAR. 

